New advanced oxidation technologies of water and wastewater treatment (part 2) (foreign publications review)

Summary

Newly developed oxidation technologies are applied in purification of water and wastewater containing toxic for microorganisms and non-biodegradable substances. Ultrasonic treatment provides for good results; however requires expensive equipment and much energy. The efficiency of this technology can be improved by using catalysts (titanium dioxide) and chemical additives; it is used as a process preceding biological treatment. Wet oxidation is considered as a perspective method of processing phosphorus-containing wastewater sludge. The process proceeds in the presence of oxygen at 160–220 °С and 12–28 bar pressure with addition of sulfuric acid (рН 1.5). The technology of oxidation in supercritical water is based on interaction of organic pollutants with oxidizers in homogenous supercritical medium. The process is carried out at 400–650 °С temperature and 220–350 bar pressure. Experiments of inactivating Escherichia coli bacteria in river water with the use of impulse corona discharge (inactivation rate 99.8%) were carried out. The technology of plasma water treatment was tested on laboratory scale so far. The use of alkali metal ferrates (VI) that provide for removing suspended solids, phosphates, and reducing COD and BOD is considered as a perspective method of water treatment. Electrochemical processes are characterized by flexibility, safety, selectivity and higher cost-effectiveness; they allow eliminating ammonium and nitrates from wastewater. The use of combined process flow schemes can result in the reduction of operating expenditures at higher water treatment efficiency compared to the use of separate oxidation technologies. It is supposed that as research and design in this area advance the number of industrial scale plants using combined wastewater treatment flow schemes will grow.

Key words

advanced oxidation technologies , wet oxidation , supercritical water , plasma treatment , ferrates , electrochemical process